INDICATOR POSITION DETECTING DEVICE AND INDICATOR POSITION DETECTING METHOD

• US 20110241651A1
• Filed: 02/10/2011
• Published: 10/06/2011
• Est. Priority Date: 03/30/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Oda, Yasuo
• Granted Patent: US 8,604,808 B2
• Time in Patent Office: Days
• US Class Current: 324/76.39
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

An indicator position detecting device and method are provided, which allow accurate position detection without the influence of noise in detection of the position of an indicator (e.g., a finger, a stylus pen) by a capacitive coupling system. To a conductor pattern in which plural conductors for signal transmission and plural conductors for signal reception intersect with each other, signals with frequencies different from each other are simultaneously supplied to the plural conductors on the transmission side, and signals of respective frequencies corresponding to the plural signals with the different frequencies are detected on the reception side, to thereby detect the position of an indicator on the conductor pattern. The amount of noise of each of the detected frequencies is detected. Any frequency that cannot be properly detected due to noise is switched to another frequency, and detection is carried out based on the newly selected frequency.

Claims

1. An indicator position detecting device, comprising:

a conductor pattern that is composed of a plurality of conductors disposed along a first direction and a plurality of conductors disposed along a second direction intersecting with the first direction, the conductor pattern being configured to detect position indication by an indicator,

a multi-frequency signal supply circuit configured to supply a plurality of signals with different frequencies to the plurality of conductors disposed along the first direction,

a frequency analyzing circuit configured to be supplied with signals from the plurality of conductors disposed along the second direction and to carry out frequency analysis of a signal based on position indication by the indicator with respect to the conductor pattern,

an indicated-position detecting circuit configured to be supplied with a signal from the frequency analyzing circuit and to detect position indication by the indicator with respect to the conductor pattern,

a noise analyzing circuit configured to carry out frequency analysis of a noise signal received by the conductor pattern, and

a control circuit configured to control allocation of frequencies of multi-frequency signals supplied from the multi-frequency signal supply circuit to the plurality of conductors disposed along the first direction based on frequency analysis of a noise signal by the noise analyzing circuit.

2. The indicator position detecting device according to claim 1, further comprising a transmitting conductor selection circuit configured to group the plurality of conductors disposed along the first direction into a plurality of blocks, to switch between the respective blocks in a time-division manner, and to supply multi-frequency signals generated by the multi-frequency signal supply circuit to the plurality of conductors that make up each block.

3. The indicator position detecting device according to claim 1, further comprising a receiving conductor selection circuit configured to group the plurality of conductors disposed along the second direction into a plurality of blocks, to switch between the respective blocks in a time-division manner, and to supply signals from the plurality of conductors that make up each block to the frequency analyzing circuit.

4. The indicator position detecting device according to claim 1, wherein the noise analyzing circuit configured to carry out frequency analysis of a noise signal received by the conductor pattern is configured to analyze frequency of a noise signal received by the conductor pattern in a period during which multi-frequency signals from the multi-frequency signal supply circuit are not supplied to the plurality of conductors disposed along the first direction.

5. The indicator position detecting device according to claim 1, wherein the noise analyzing circuit configured to carry out frequency analysis of a noise signal received by the conductor pattern is configured to carry out frequency analysis for each frequency allocated as a multi-frequency signal supplied to the conductor pattern.

6. The indicator position detecting device according to claim 1, further comprising an amplification circuit configured to amplify signals from the conductors disposed along the second direction, wherein

a reception level with respect to all frequency components included in signals from the conductors disposed along the second direction is obtained, and amplification control of the amplification circuit is carried out according to the reception level.

7. The indicator position detecting device according to claim 1, wherein a signal level of a multi-frequency signal generated in the multi-frequency signal supply circuit is controlled based on a reception level of signals from the conductors disposed along the second direction.

8. The indicator position detecting device according to claim 1, further comprising a phase control circuit configured to control the relative phases among respective signals supplied to the plurality of conductors disposed along the first direction.

9. The indicator position detecting device according to claim 1, wherein

the multi-frequency signal supply circuit is further configured to generate signals of a plurality of frequencies in a first group and signals of a plurality of frequencies in a second group, and

the control circuit is configured to instruct, based on frequency analysis of a noise signal by the noise analyzing circuit, the multi-frequency signal supply circuit to selectively supply the signals of the plurality of frequencies in the first group or the signals of the plurality of frequencies in the second group to the plurality of conductors disposed along the first direction.

10. The indicator position detecting device according to claim 1, wherein

the multi-frequency signal supply circuit is further configured to generate a signal of a spare frequency, and

the control circuit is configured to instruct, based on frequency analysis of a noise signal by the noise analyzing circuit, the multi-frequency signal supply circuit to change a frequency of a multi-frequency signal supplied to the plurality of conductors disposed along the first direction from a frequency corresponding to the noise signal to the spare frequency.

11. The indicator position detecting device according to claim 10, wherein the control circuit is configured to notify the frequency analyzing circuit of a change from the frequency corresponding to the noise signal to the spare frequency, such that the frequency analyzing circuit analyzes the spare frequency instead of the frequency corresponding to the noise signal.

12. The indicator position detecting device according to claim 1, wherein the control circuit is configured to control, based on frequency analysis of a noise signal by the noise analyzing circuit, allocation of frequencies of multi-frequency signals supplied from the multi-frequency signal supply circuit to the plurality of conductors disposed along the first direction, and to control allocation of frequencies to be analyzed in the frequency analyzing circuit.

13. The indicator position detecting device according to claim 1, wherein a signal of a high frequency among the plurality of signals with the different frequencies generated by the multi-frequency signal supply circuit is supplied to a conductor disposed along the first direction on a side of the conductor pattern that is coupled to the frequency analyzing circuit.

14. An indicator position detecting method, comprising:

a multi-frequency signal supply step of supplying a plurality of signals with different frequencies to a plurality of conductors disposed along a first direction, in a conductor pattern for detecting position indication by an indicator, the conductor pattern being composed of the plurality of conductors disposed along the first direction and a plurality of conductors disposed along a second direction intersecting with the first direction,

a frequency analysis step of carrying out frequency analysis of signals from the plurality of conductors disposed along the second direction,

an indicated-position detection step of being supplied with a signal subjected to the frequency analysis in the frequency analysis step and detecting position indication by the indicator with respect to the conductor pattern,

a noise analysis step of carrying out frequency analysis of a noise signal received by the conductor pattern, and

a control step of controlling allocation of frequencies of multi-frequency signals supplied to the plurality of conductors disposed along the first direction in the multi-frequency signal supply step based on the frequency analysis of the noise signal in the noise analysis step.